feat(backend): approximate distinct-source count for Sentinel rejections #29

Merged

starkSV merged 2 commits from feat/sentinel-distinct-sources into main

2026-07-13 12:46:06 +05:30

starkSV commented

2026-07-13 12:45:42 +05:30

(Migrated from github.com)

Summary

Adds an all-time Sentinel-rejection counter and an approximate distinct-source count (Redis HyperLogLog seeded from the reporting IP, no raw IPs stored)
/metrics now exposes flat sentinel_errors and sentinel_distinct_sources_est fields

Why

CLI telemetry showed a growing count of Sentinel rejections with no way to tell whether they come from one user retrying repeatedly or many distinct users independently getting blocked

Test plan

Backend builds clean, go vet passes
Verified PFAdd/PFCount compile against the redis client (build succeeds)
After merge: redeploy backend, check /metrics for the new fields once a Sentinel error occurs

Summary by CodeRabbit

Bug Fixes
- Improved reliability when generating Microsoft download links by ensuring session cookies are available for requests.
New Features
- Added Sentinel error tracking and distinct-source estimates to telemetry.
- Exposed Sentinel error statistics through the metrics endpoint.

## Summary - Adds an all-time Sentinel-rejection counter and an approximate distinct-source count (Redis HyperLogLog seeded from the reporting IP, no raw IPs stored) - /metrics now exposes flat sentinel_errors and sentinel_distinct_sources_est fields ## Why - CLI telemetry showed a growing count of Sentinel rejections with no way to tell whether they come from one user retrying repeatedly or many distinct users independently getting blocked ## Test plan - Backend builds clean, go vet passes - Verified PFAdd/PFCount compile against the redis client (build succeeds) - After merge: redeploy backend, check /metrics for the new fields once a Sentinel error occurs  ## Summary by CodeRabbit * **Bug Fixes** * Improved reliability when generating Microsoft download links by ensuring session cookies are available for requests. * **New Features** * Added Sentinel error tracking and distinct-source estimates to telemetry. * Exposed Sentinel error statistics through the metrics endpoint.

coderabbitai[bot] commented

2026-07-13 12:46:01 +05:30

(Migrated from github.com)

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: eb903836-26e2-4bfc-a49b-1f65ff460848

📥 Commits

Reviewing files that changed from the base of the PR and between 6e374e6a45 and 327c5e195d.

📒 Files selected for processing (1)

backend/main.go

📝 Walkthrough

Walkthrough

The pull request initializes missing session cookie jars for Microsoft download-link requests and adds Redis-backed Sentinel failure counts and distinct-source estimates to telemetry and metrics responses.

Changes

Download request cookie handling

Layer / File(s)	Summary
Initialize the download request cookie jar `backend/main.go`	The Microsoft download-link request now creates a `simpleCookieJar` when the session jar is missing or legacy.

Sentinel telemetry aggregation

Layer / File(s)	Summary
Record and expose Sentinel statistics `backend/main.go`	Failed telemetry containing “Sentinel” updates a Redis counter and HyperLogLog, and `/metrics` returns the resulting error count and distinct-source estimate.

Estimated code review effort: 2 (Simple) | ~10 minutes

✨ Finishing Touches

📝 Generate docstrings

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch feat/sentinel-distinct-sources

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain main module or its selected dependencies"

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[![Review Change Stack](https://storage.googleapis.com/coderabbit_public_assets/review-stack-in-coderabbit-ui.svg)](https://app.coderabbit.ai/change-stack/starkSV/windows-iso-downloader/pull/29?utm_source=github_walkthrough&utm_medium=github&utm_campaign=change_stack)   > [!CAUTION] > ## Review failed > > The pull request is closed.  <details> <summary>ℹ️ Recent review info</summary> <details> <summary>⚙️ Run configuration</summary> **Configuration used**: defaults **Review profile**: CHILL **Plan**: Pro Plus **Run ID**: `eb903836-26e2-4bfc-a49b-1f65ff460848` </details> <details> <summary>📥 Commits</summary> Reviewing files that changed from the base of the PR and between 6e374e6a45209a4db2a8a90764685edc604bcbbf and 327c5e195dfc9d77ee89e1fee0ad5b8812e92588. </details> <details> <summary>📒 Files selected for processing (1)</summary> * `backend/main.go` </details> </details> ---  <details> <summary>📝 Walkthrough</summary> ## Walkthrough The pull request initializes missing session cookie jars for Microsoft download-link requests and adds Redis-backed Sentinel failure counts and distinct-source estimates to telemetry and metrics responses. ### Changes **Download request cookie handling** |Layer / File(s)|Summary| |---|---| |**Initialize the download request cookie jar** <br> `backend/main.go`|The Microsoft download-link request now creates a `simpleCookieJar` when the session jar is missing or legacy.| **Sentinel telemetry aggregation** |Layer / File(s)|Summary| |---|---| |**Record and expose Sentinel statistics** <br> `backend/main.go`|Failed telemetry containing “Sentinel” updates a Redis counter and HyperLogLog, and `/metrics` returns the resulting error count and distinct-source estimate.| **Estimated code review effort:** 2 (Simple) | ~10 minutes </details>   <details> <summary>✨ Finishing Touches</summary> <details> <summary>📝 Generate docstrings</summary> - [ ]  Create stacked PR - [ ]  Commit on current branch </details> <details> <summary>🧪 Generate unit tests (beta)</summary> - [ ]  Create PR with unit tests - [ ]  Commit unit tests in branch `feat/sentinel-distinct-sources` </details> </details>   > [!WARNING] > There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure. > > <details> > <summary>🔧 golangci-lint (2.12.2)</summary> > > level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain main module or its selected dependencies" > > > > > </details>   --- Thanks for using [CodeRabbit](https://coderabbit.ai?utm_source=oss&utm_medium=github&utm_campaign=starkSV/windows-iso-downloader&utm_content=29)! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out. <details> <summary>❤️ Share</summary> - [X](https://twitter.com/intent/tweet?text=I%20just%20used%20%40coderabbitai%20for%20my%20code%20review%2C%20and%20it%27s%20fantastic%21%20It%27s%20free%20for%20OSS%20and%20offers%20a%20free%20trial%20for%20the%20proprietary%20code.%20Check%20it%20out%3A&url=https%3A//coderabbit.ai) - [Mastodon](https://mastodon.social/share?text=I%20just%20used%20%40coderabbitai%20for%20my%20code%20review%2C%20and%20it%27s%20fantastic%21%20It%27s%20free%20for%20OSS%20and%20offers%20a%20free%20trial%20for%20the%20proprietary%20code.%20Check%20it%20out%3A%20https%3A%2F%2Fcoderabbit.ai) - [Reddit](https://www.reddit.com/submit?title=Great%20tool%20for%20code%20review%20-%20CodeRabbit&text=I%20just%20used%20CodeRabbit%20for%20my%20code%20review%2C%20and%20it%27s%20fantastic%21%20It%27s%20free%20for%20OSS%20and%20offers%20a%20free%20trial%20for%20proprietary%20code.%20Check%20it%20out%3A%20https%3A//coderabbit.ai) - [LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fcoderabbit.ai&mini=true&title=Great%20tool%20for%20code%20review%20-%20CodeRabbit&summary=I%20just%20used%20CodeRabbit%20for%20my%20code%20review%2C%20and%20it%27s%20fantastic%21%20It%27s%20free%20for%20OSS%20and%20offers%20a%20free%20trial%20for%20proprietary%20code) </details> <sub>Comment `@coderabbitai help` to get the list of available commands.</sub>